Perspective on improving the quality of surface and material data analysis in the scientific literature with a focus on x-ray photoelectron spectroscopy (XPS)

Abstract

Due to significant advances in instrumentation, many previously specialized techniques have become “routine” in user facilities. However, detailed knowledge held by experts has often not been relayed to general users, so they often rely on entry-level information, basic principles, and comparison with literature results for data analysis. As a result, major errors in the data analysis of multiple surface and material analysis techniques, including in x-ray photoelectron spectroscopy (XPS), have been appearing in the scientific literature. Representative examples of serious errors in XPS data analysis are shown in this work. We suggest that surface and material analysis, and perhaps even science in general, are in a state of “pre-crisis.” We use two (logistic) models from population biology to suggest that bad analyses self-correct if they remain below a critical number. However, beyond a threshold, the literature can become useless because of the perpetuation of faulty analyses and concomitant loss of its self-correcting ability. XPS is used by scientists in many communities because of the power of the technique and high-quality instrumentation that is commercially available. Those who make new surfaces and materials face unique challenges because of the large number of surface and material analytical techniques that are often needed to characterize their materials. Graduate students and post-docs are often provided with only minimal instruction on using surface and material characterization methods. High fees for instruments may affect both the quality and the quantity of the data people collect. The Prisoner's Dilemma is a model from game theory that describes situations with reward structures that encourage uncooperative behavior and lead to suboptimal outcomes. However, the outcomes of Prisoner's Dilemma are not inevitable—their consequences change if their reward structures change. The current system does not appear to incentivize detailed learning of surface and material characterization techniques and careful material characterization. Prisoner's dilemmas appear to lead to other undesirable consequences in science. The concerns raised in this work suggest that many manuscripts are incompletely reviewed at present. The different stakeholders in this problem, including authors, research advisers, subject matter experts, reviewers, scientists who notice examples of faulty data analysis, editors, journals and publishers, funding agencies, scientific societies, leaders at universities and research centers, and instrument vendors, can improve the current situation. This work provides specific recommendations for each of these stakeholders. For example, we believe that authors are primarily responsible for the correctness of their work, not reviewers or editors; we question the wisdom of listing the names of the editor and reviewers on a paper; we are grateful for the significant contributions that have been made by subject matter experts to produce standards and tutorial information; the high cost of instrument time at some institutions may limit student access and result in suboptimal analyses; staff scientists often need to be better recognized for their intellectual contributions to studies; publishers may wish to allow selective reviewing of specific sections of papers related to material characterization; the reviewing at some open access journals may be inadequate; while it had its shortcomings, the pre-open access model of publishing incentivized the production and publication of high-quality work; audits of the products (scientific papers) of funding agencies may be necessary; collaboration needs to be encouraged to a greater extent at some institutions; and instrument vendors should not suggest to potential customers that surface characterization, e.g., by XPS, is trivial or simple.

Enhanced Thermoelectric Performance of Mg–Sn Thin Films: Role of Mg9Sn5 Phase and One-Dimensional Electronic Structure

“…The deconvolution and quantification of the spectra were executed using the XPSPEAK41 software. 49 Gaussian−Lorentzian sum functions and Shirley background types were used to fit the XPS spectra. High-resolution narrow scans, as depicted in Figure 6, were employed to examine the core-level elements, including Mg 1s, Mg 2p, and Sn 3d, in the Mg−Sn films.…”

Toward an increased reliability of chemical bonding assignment in insulating samples by x-ray photoelectron spectroscopy

“…The additional advantage is that such referenced BE values can be directly compared to the gas phase measurements. If, however, a work function measurement is not feasible, we propose to drop the absolute energy referencing practiced today for the sake of substantially improved accuracy in chemical-state determination, which is the primary goal of XPS analyses ( 55 ). The latter scenario is based on the observation that the BE difference between peaks from an insulator and the C 1s peak of the related AdC layer is constant (confirmed here for alumina films in the thickness range of 2 ≤ d Al 2 O 3 ≤ 467 nm), as both share a common VL.…”

Surface analysis insight note: Multivariate curve resolution of an X‐ray photoelectron spectroscopy image

“…Other surface and material characterization methods are similarly being applied incorrectly 25 . In response to this state of precrisis, 26 the XPS community has produced a great deal of tutorial information on the technique. For example, a recent special issue of the Journal of Vacuum Science and Technology focused on various aspects of XPS 3,4,27–34 .…”